This paper might seem too scientific, but is very important for the discussions about a EU wide regulation on THC residuals in hemp food, which is only being created.

Uncertainty factors are used to compensate for a deficiency in knowledge concerning the accuracy of test results and the difficulty in estimating the health effects in a different species and/or in different exposure conditions.

Especially compared to caffeine (5.7 mg/kg bw is the EFSA-limit, even though anxiety can already occur at 3 mg/kg bw), nicotine (no LOAEL-NOAEL correction there) and alcohol (no risk assessment was performed for alcohol in food, even though research shows that it is warranted), THC is treated unfairly.
There seems to be a trend to have lower UFs for other substances compared to THC even though their endpoints are more severe. The mild and transient effects of THC should not be held to the same UF-guidelines as the severely adverse and possibly terminal effects opium alkaloids can have.